Roller clutch assemblies have three basic components, a roller clutch and a pair of roller clutch races between which the roller clutch is located. Each race has a generally cylindrical inner surface which, when the races are maintained coaxial to one another, define a generally annular space between the races. The inner surface of one race, the pathway race, is completely smooth and cylindrical, while the other, the cam race, has a V notched, saw tooth configuration.
The roller clutch has a cage that retains a plurality of rollers and springs as a secure subassembly for easy handling and installation. The clutch cage is sized so as to fit between the clutch races, and is generally described as being installed in the annular space between the races. However, those skilled in the art understand that situations where the roller clutch could actually be installed directly into an already formed annular space would be rare. For one thing, it is usually only the presence of roller clutch between the races that creates the annular space in the first instance. More importantly, it is usually desirable to install the clutch to the cam race first, and then install the pathway race last by the so called ringing in method, with its simultaneous axial push and angular twist. This is so because each roller is typically retained to the cage before installation by its own individual energizing spring, which keeps the roller resiliently loaded forward against a roller rest surface on the cage. In order for the roller to operate properly after clutch installation, it has to be shifted back away from its cage rest surface, so that it can travel back and forth without hitting the rest surface. The twisting motion of the pathway race is what shifts the rollers safely away from their cage rest surfaces.
Spring dependent roller retention depends on the roller pocket staying square or parallel to the cage axis. If the pocket is tipped off axis during installation, the roller may fall out. In order to be able to install the clutch to the cam race alone without losing the rollers, it is important that the orientation of the pockets not be disturbed to too great a degree. One known means of fixing the cage to the cam race alone is called the twist lock method. The clutch cage is provided with retention ears which fit through the notches created by the cam ramps, thereby allowing the cage to be pushed axially straight onto the cam race without binding. Then, the cage is twisted through a small angle, which shifts the retention ears into abutment with the end faces of the cam race, preventing the cage from shifting axially relative to the cam race. None of the twist and lock cage installation motions disturb the orientation of the roller pockets relative to the cage axis, so roller retention is not jeopardized. While the twist lock method provides adequate retention of the cage to the cam race, it does require that the retention ears be exposed on the face of the cam race, which might be undesirable in some applications. An example of a twist lock cage may be seen in Lederman U.S. Pat. No. 4,712,661, assigned to the assignee of the subject invention.
One patent, Groh U.S. Pat. No. 4,821,857, does disclose a means of fixing the clutch cage to the cam race without using exposed retention ears. However, the installation scheme apparently relies on inserting the clutch directly into an annular space between a pair of races that are already maintained in coaxial relation. In Groh, a folded metal roller cage 11 consists of two axially spaced side disks, 13 and 18, joined together by cross bars 15 and 22. Cylindrical rollers 36 are retained parallel to the axis of cage 11 in pockets formed between the side disks 13 and 18, by some means not described in detail. One side disk, 13, is designed to fit between the races 27 and 29 without interference. Side disk 18, however, has a diameter designed to force it into the cam race 29 as cage 11 is inserted, thereby flexing it radially inwardly. Disk 18 eventually snaps back out into a groove 33 cut into cam race 29. If cage 11 were installed just to cam race 29, the flexing in of the one side disk 18 would cause cage 11 to go conical, often called bellmouthing, which would tilt the roller pockets off axis. This would jeopardize the retention of the rollers 36 if the pathway race 27 were not already in position. But, as noted, instances where the clutch races are already in coaxial relation are rare. Another drawback of the Groh installation scheme is that the groove 33, as well as the ultimate location of the flexible side disk 18, are well of inboard the end faces of the races. It would be difficult to apply any twisting motion to the cage 11 as it was pushed in, at least once the side disk 18 had moved beyond the end faces of the races. It would, therefore, also be difficult to shift the rollers 36 back away from their forward loaded shipping position. In fact, FIG. 2 of Groh appears to show the rollers right against the cage cross bars.